My debit card keeps getting declined by Apple. Although the balance is enough to clear my pending purchases. What do I do?

My debit card keeps getting declined by Apple. Although the balance is enough to clear my pending purchases. What do I do? I have tried adding other cards and apple keeps declining them too. Another error I keep getting is that there is a problem with my payment method but this is a payment method I use on a daily for transactions on Spotify, Netflix etc. I really need help with this please as I cannot download apps or update or renew my subscriptions.